This invention relates in general to the field of dentistry and, more particularly, to an apparatus for use in preparing crowns for posterior teeth. Moreover, this invention relates to methods for preparing dental crowns and for preparing replacement dental structures.
An important aspect of an individual's overall physical health is good oral hygiene. When a tooth becomes damaged or diseased it is imperative that the problem be remedied. Damaged or diseased teeth, such as molars, bicuspids and anterior teeth, are often repaired by the addition of a dental crown to the affected tooth. Sometimes the tooth must be removed completely and replaced by an imitation dental structure.
As can be appreciated, great care must be taken when preparing dental crowns or replacement teeth. The replacement dental work must conform to the opposing dental structures so as to not alter the occlusal characteristics, or bite, of a patient's teeth. The replacement dental work must also be capable of being done in a timely manner.
The first step in preparing replacement dental work is for the dentist to prepare the damaged or diseased tooth. For a posterior tooth, this normally consists of grinding the tooth to a base structure. For an anterior tooth, this either requires extraction of the tooth or grinding the tooth to a base structure. The dentist then takes an impression of the patient's entire dental structure, both top and bottom sets of teeth. From these impressions, a model of the patient's dental structures is prepared. This model is often referred to as fractory work. This model is a replica of the patient's set of teeth and the top and bottom sets of teeth are coupled together by a hinge or the like in a manner corresponding to the patient's occlusal characteristics. The model is cut up or sectioned into as many pieces as necessary so that the technician preparing the dental work can work easily with the individual replica of the tooth needing repair.
Currently, the most widely utilized method for preparing a metal crown for a posterior tooth starts by removing the replica of the tooth to be crowned from the model and dipping the tooth in a wax or other similar substance to form a thin coat around the tooth. The replica tooth is often referred to as being "waxed-up" at this point. The tooth has previously been coated with a lubricant so that the wax impression may be removed from the replica. Additional wax is then transferred to the "waxed-up" replica to build a wax crown that corresponds to the occlusal characteristics of the tooth's opposing dental structure. Obtaining the correct occlusal and anatomical characteristics on this wax tooth is done by the technician visually attempting to copy the correct characteristics, especially the custip or contact points of one tooth with its opposing teeth, on a trial and error basis whereby wax is added or cut away until the technician believes a properly formed tooth is prepared. As can be seen, this requires a great deal of knowledge of proper dental anatomy and an artist's skill in transferring the characteristics of the opposing dental structure or structures to the wax crown being prepared. Once a satisfactory wax crown is obtained, the wax crown is removed from the replica of the tooth and converted into a metal crown for permanent placement on the patient's tooth.
If a porcelain crown is to be prepared, essentially the same method is utilized except that only a thin layer of metal is first prepared from the "waxed-up" replica as the underlying base structure of the crown. Porcelain material is then added onto this metal base structure again until the technician believes that the proper occlusal and anatomical characteristics of the damaged tooth to its opposing dental structures is formed. Again, this requires a great deal of time and skill to prepare a proper and accurate porcelain crown.
Replacement anterior teeth are typically prepared by a similar trial and error method where the porcelain is added to a base metal structure by the technician until it is believed that the proper occlusal and anatomical characteristics of the tooth have been obtained.
As can be seen, the methods currently employed in preparing replacement dental work are time consuming in that a trail and error method is utilized. Additionally, no uniformity or consistency from one crown to the next is possible since each individual crown or replacement dental structure is dependent upon the skill of the technician preparing that particular replacement dental structure. The importance of having the replacement dental work correspond accurately to its opposing dental structures is paramount in maintaining the integrity of the patient's occlusal characteristics and much accuracy is lost when the preparation of the crown or other dental work relies upon the skill of the technician in visually copying the anatomical characteristics of the dental structures involved.
It is therefore a primary object of the present invention to provide an apparatus for use in preparing dental crowns that enables crowns to be made quickly and accurately that correspond to the the proper occlusal and anatomical characteristics of the patient's dental structures without relying upon the individual artistic skill of the technician involved.
It is a further object of the present invention to provide such an apparatus that can be positioned so that the proper custip or contact points of the tooth to be crowned with its opposing dental structures can be integrated into the crown without the need for guesswork or artistic ability on the part of the technician.
It is another object of the present invention to provide an apparatus for use in preparing dental crowns that has a plurality of pathways and a plurality of upright supports that enable the custip points of the opposing dental structure to be properly positioned on the crown being prepared.
It is still another object of the present invention to provide such an apparatus having caps on the top of the upright supports so as to pinpoint the location of the custip points on the crown being prepared.
It is an aim of the present invention to provide a method for preparing metal or porcelain crowns utilizing the apparatus of the present invention that produces anatomically accurate dental crowns without relying on a technician's skill or ability.
It is still another aim of the present invention to provide a preformed wax crown comprising at least four individual, separate layers that correspond to the layers of porcelain and metal utilized when preparing replacement porcelain dental structures.
It is still another aim of the present invention to provide such preformed, four-layered, wax crowns in a variety of sizes to accommodate most normally sized dental structures.
It is yet another aim of the present invention to provide a preformed, four-layered, wax crown that is adapted for use in preparing porcelain crowns or replacement porcelain dental structures for anterior teeth.
It is an additional aim of the present invention to provide methods for preparing dental crowns for anterior or posterior teeth utilizing the preformed, four-layered, wax crowns in a manner that produces anatomically correct crowns or replacement dental structures quickly and accurately without relying on the individual artistic skill of the technician.
It is a still further aim of the present invention to provide a method and apparatus that can be utilized advantageously for preparing a full mouth restoration, such as bridges to replace dentures, that reduces the time and labor currently required in preparing such dental work.
It is also an aim of the present invention to provide apparatus and methods that are particularly adaptable to use with dental implants.
Other and further objects of the present invention will become apparent from the following description of the invention and the accompanying drawings.